Firefighters are warning parents of a dangerous craze where children are setting fire to huge bails of hay and rolling them down hillsides.

As farmers begin to harvest their crops, the one-tonne bails are proving tempting targets for arsonists.

In the latest incident, a crew from Swalwell Fire Station was called out at 10pm yesterday to deal with a bail which had crashed through a fence overlooking the Tanfield Railway, near Sunniside.

Sub Officer Barry Clark said he was extremely concerned about the craze. He said: "Apart from being criminal damage, you can imagine what would happen if a bail hit someone. We have had two or three incidents and I know there has been one in Sunderland.

"It's a foolish game to play. It's surprising how easy it is to move the bails but they are difficult to stop."